How to determine whether a string is a number in javascript

In JavaScript, you can use the Number() function and isNaN() function to determine whether a string is a number. The syntax is "isNaN(Number("String",10)"; if true is returned, then the The string is not a number, otherwise it is a number.

The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.

javascript determines whether a string is a number

In the process of converting a string into a number through Number(), if the string contains non-numbers, then Will return NaN, refer to the following code

Number("Hello",10);//return NAN  
Number("110",10);//return 110 
Number("t2110",10);//return NAN  
Number("1f10g",10);//return NAN

So you can use isNaN() to determine whether the return value of Number() is NaN to determine whether the string is a number. If it returns true, the string is not a number, otherwise it is a number.

Implementation code:

function f(a){
	if(isNaN(Number(a,10))){
		console.log("不是数字");
	}
	else{
		console.log("是数字");
	}
}

Test:

f("hello");
f("10");
f("d10jh5");
f("10jh5");

Note: You cannot use the following method to judge:

Number("Hello",10)==NaN;//return false  
Number("110",10)==NaN;//return false

Because NaN and itself do not want to wait, this is quite special. The way to judge NaN is isNaN().

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